Encapsulation compositions

ABSTRACT

Carbohydrate-based glassy matrices which are stable in the glassy state at ambient temperatures may be prepared by the use of aqueous plasticizers with melt extrusion. Such glassy matrices are useful for the encapsulation of encapsulates, in particular, flavoring agents.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to encapsulation compositions inwhich an encapsulate is encapsulated in a glassy matrix. Moreparticularly, the present invention relates to flavor encapsulationcompositions in which a flavoring agent is encapsulated in a glassymatrix.

[0003] 2. Discussion of the Background

[0004] The encapsulation of encapsulates is an area of active research.In particular, the encapsulation of encapsulates such as medications,pesticides (including insecticides, nematocides, herbicides, fungicides,microbicides, etc.), preservatives, vitamins, and flavoring agents isdesired for a number of reasons. In the case of medications andpesticides, such encapsulation may be desired to achieve the controlledrelease of the medication or pesticide. In the case of vitamins, theencapsulation may be carried out to protect the vitamin fromair-oxidation and, thus, to extend the shelf life of the vitamin. In thecase of a flavoring agent, the encapsulation may be carried out to placethe flavoring agent in an easily metered form which will release theflavoring agent at a controllable event, such as the addition of water.

[0005] It is generally known to skilled practitioners in the field offlavor encapsulation that current practical commercial processes leadingto stable, dry flavors are generally limited to spray drying andextrusion fixation. The former process requires the emulsification orsolubilization of the flavor in a liquid carrier containing theencapsulating solids, followed by drying in a high temperature, highvelocity gas stream and collection as a low bulk density solid.

[0006] While spray drying accounts for the majority of commercialencapsulated materials, several limitations of the process are evident.Low molecular weight components of complex or natural flavor mixturesmay be lost or disproportionate during the process. The resultantflavor-carriers are porous and difficult to handle. In addition,deleterious chemical reactions such as oxidation can result on surfacesexposed during and after drying. The final product, a dry, free flowingpowder, will release the encapsulant rapidly upon rehydration whetherrapid release is desired or not.

[0007] U.S. Pat. No. 3,971,852, to Brenner et al., teaches the use ofmodified starch, gums and other natural hydro-colloids with lowermolecular weight polyhydroxy compounds to yield a glassy cellular matrixwith encapsulated oil at a maximum of 80 volume %. This system forms ashell surrounding the oil flavoring but is limited to lipophilicflavoring agents. Saleeb and Pickup, in U.S. Pat. No. 4,532,145,describe a process and composition in which a volatile flavorant isfixed by spray drying from a carrier solution made up of 10-30% of a lowmolecular weight component such as a sugar or an edible food acid withthe balance of solids being a maltodextrin carbohydrate in the amount of70-90%. U.S. Pat. No. 5,124,162, to Boskovic et al., discloses a carriermixture composed of mono- and disaccharides (22-45%), maltodextrins(25-50%), and a high molecular weight carbohydrate such as gum arabic,gum acacia or chemically modified starch (10-35%) to which flavoringagents are added and the subsequent solution spray dried to yield a freeflowing powder with a bulk density of 0.50 g/cc.

[0008] Several technical issues unmet by these approaches cited areevident. Firstly, thermally sensitive flavors undergo undesirablereactions, including oxidations, rearrangements and hydrolyses.Secondly, volatile components are lost during the atomization andevaporation in the dryer.

[0009] A second process route, that of melt encapsulation, has beenutilized to advantage with lipid-based flavors. In this technology amelt is prepared in the form of a high solids carbohydrate syrup,flavoring oils with emulsifier are added under pressure, agitated, anddispersed, and the mixture is injected into a chilling, dehydratingsolvent bath to obtain fine, rod-like filaments. After the solventremoval, the matrix is reduced in size and, in some cases, coated withanti-caking agents before being packed. Description of the keyparameters of this process can be found in the U.S. Pat. Nos. 2,809,895and 3,0410,180, to Swisher, U.S. Pat. Nos. 2,856,291 and 2,857,281, toShultz, U.S. Pat. No. 3,704,137, to Beck, and subsequent improvements inthe art are detailed in U.S. Pat. No. 3,314,803 for encapsulation ofvolatiles such as acetaldehyde.

[0010] An alternative route to encapsulating flavorings is taught bySair and Sair, in U.S. Pat. No. 4,230,687. In this approach, highmolecular weight carriers such as proteins, starches or gums areplasticized by addition of water in the presence of the encapsulate andsubjected to a high shear dispersive process. The dispersed matrix plusencapsulate is then recovered and dried to yield a stable product.

[0011] Another alternative process, melt extrusion, can be utilized forflavor fixation and encapsulation. In this process, a melting system,i.e. an extruder, is employed to form the carrier melt in a continuousprocess. The encapsulate flavor is either admixed or injected into themolten carbohydrate carrier. Saleeb and Pickup teach, in U.S. Pat. No.4,420,534, use of a matrix composition consisting of 10 to 30 wt % of alow molecular weight component chosen from a series of mono- ordisaccharides, corn syrup solids, or organic acid with the balance ofthe mixture being maltodextrin. The matrix base is dry blended with ananhydrous liquid flavoring component and melted in a single screwextruder to yield a solid matrix characterized as a glass with a glasstransition temperature >40° C.

[0012] Levine and Slade, in U.S. Pat. Nos. 5,087,461 and 5,009,900,teach a similar approach utilizing a composition consisting of amodified food starch, maltodextrin, polyol, and mono- and disaccharidecomponents. The starch is a chemically modified, water-soluble starchand is used in an amount of 40 to 80% of the total mixture. The balanceof the composition is comprised of 10-40% of maltodextrin, 5 to 20% ofcorn syrup solids or polydextrose and 5-20% of mono- or disaccharide.This matrix is made to balance processing response with glass matrixcharacter.

[0013] In the two preceding examples in the '461 and '900 patents, thematrix composition was carefully defined to accommodate the processinglimitations of the extruder as well as to generate a stable matrix beingin the glassy state and characterized by a glass transition temperatureof >40° C.

[0014] Formation of a matrix in the glass state is of particular valuefor encapsulation of water-soluble flavorings and extracts. In thesecases, the role of water as a plasticizing agent conflicts with thisdesired result, because water in the final product has the effect oflowering the glass transition temperature (T_(g)) of the glassy matrix.In model studies of a number of food carbohydrate systems, the upperlimit of water content is approximately 7-10 wt. % for lower molecularweight components such as mono- and disaccharides, maltodextrins andcombinations of these agents. At higher water contents, the T_(g) islowered to the extent that the matrix is in the undesirable rubbery orplastic state at room temperature.

[0015] In order to insure higher T_(g)'s there are several optionsavailable. By limiting the class of encapsulate materials to lipophilicmaterials such as citrus oils, plasticizing moisture may be removed by aboil off process as described in U.S. Pat. No. 2,809,895. Alternatively,the use of melt encapsulation as taught in U.S. Pat. No. 4,420,534limits the flavoring agents to materials with lower vapor pressure whichcan be admixed to the premelt composition. In addition, flavorings whichare in the form of aqueous extracts, water, and alcohol-water solutionswill result in a product with a T_(g) much below 25° C. leading toplastic flow and loss of volatiles upon storage.

[0016] Similarly, in U.S. Pat. No. 5,009,900, the flavorings are limitedto those with limited volatility and total moisture levels in the finalproduct are less than 11% by weight. Many of the key topnotes and uniqueflavor components of complex flavors have high vapor pressures at roomtemperature and are not easily encapsulated by such a process.

[0017] Preparation of a solid in the glass state is dependent upon bothmatrix composition and the process used to generate the encapsulatingmaterial. The advantages of retaining the glass form of the matrix isincreased physical stability of the solid, reduced loss of incorporatedvolatiles, and reduction of deleterious intermolecular reactions. Adetailed discussion of the physical chemistry of water-food polymerinteractions as relating to the glassy state and their transitiontemperatures can be found in H. Levine and L. Slade, “Glass Transitionsin Foods”, pgs. 83-205 in Physical Chemistry of Foods, H. Schwartzbergand R. Hartel, Eds., Marciel Dekker, New York, 1992; and H. Levine andL. Slade, “Water as a Plasticizer: physico-chemical aspects oflow-moisture polymeric systems”, pgs. 79-185 in Water Science Reviews,Vol. 3, F. Franks, Ed., Cambridge University Press, London, 1988, whichare incorporated herein by reference. The role of water as plasticizerwith food polymers, as well as the relationships between molecularcomposition and dynamics of interactions between various components, arediscussed in these references.

[0018] Thus, there remains a need for encapsulation compositions inwhich an encapsulate is encapsulated in a matrix which is stable in theglass state at ambient temperatures. In particular, there remains a needfor flavor encapsulation compositions in which a flavoring agent isencapsulated in a matrix which is stable in the glassy state at roomtemperature, i.e., has a T_(g) sufficiently high to prevent caking andplastic flow at ambient temperatures. There also remains a need forflavor encapsulation compositions which have a high T_(g) and areamenable for encapsulating volatile and sensitive flavor components.

SUMMARY OF THE INVENTION

[0019] Accordingly, it is one object of the present invention to providenovel encapsulation compositions in which an encapsulate is encapsulatedin a matrix which is stable in the glassy state at ambient temperatures.

[0020] It is another object of the present invention to provide novelflavor encapsulation compositions in which a flavoring agent isencapsulated in a matrix which is stable in the glassy state at ambienttemperatures.

[0021] It is another object of the present invention to provide novelflavor encapsulation compositions which are amenable to theencapsulation of volatile or sensitive flavor components.

[0022] These and other objects, which will become apparent during thefollowing detailed description, have been achieved by the inventors'discovery that it is possible to prepare carbohydrate-based glassymatrices, which have a sufficiently high T_(g) to prevent plastic flowand caking at ambient temperatures, by interacting one or morecarbohydrate food polymers with an aqueous plasticizer in the meltingzone of an extruder and extruding the resulting mixture.

[0023] The inventors have also discovered that a composition comprising:

[0024] (A) an encapsulate, encapsulated in:

[0025] (B) a glassy matrix, comprising:

[0026] (a) 95 to 100 wt. % of a maltodextrin having 5 to 15 dextroseequivalents (D.E.); or

[0027] (b) 45 to 65 wt. % of a maltodextrin having 5 to 15 D.E. and 35to 55 wt. % of corn syrup solids having 24 to 42 D.E.; or

[0028] (c) 80 to 95 wt. % of a maltodextrin having 5 to 15 D.E., 1 to 15wt. % of a salt of an organic acid, and 0 to 15 wt. % of an organicacid; or

[0029] (d) 25 to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2 to 45wt. % of a food polymer, and 10 to 30 wt. % of a mono- or disaccharideor corn syrup solids having 24 to 42 D.E.; or

[0030] (e) 45 to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2 to 22wt. % of a carbohydrate polymer having carboxylate or sulfate sidegroups, 5 to 30 wt. % of corn syrup solids having 24 to 42 D.E., and 0.2to 2.0 wt. % of a soluble calcium salt; or

[0031] (f) 30 to 100 wt. % of a modified starch (e.g. sodium octenylsuccinate modified starch), and 0 to 70 wt. % of a mono- ordisaccharide; or

[0032] (g) 85 to 100 wt. % of a modified starch (e.g. sodium octenylsuccinate modified starch), and 0 to 15 wt. % of a polyhydric alcohol,

[0033] are stable in the glassy state, i.e., have a sufficiently highT_(g) to prevent plastic flow and caking at ambient temperature.

[0034] The present encapsulation compositions may be prepared by aprocess comprising:

[0035] (i) mixing (a), (b), (c), (d), (e), (f), or (g) with a liquidplasticizer and an encapsulate in an extruder, to obtain a meltedmatrix; and

[0036] (ii) extruding said melted matrix.

[0037] In one preferred embodiment, the present compositions areprepared by utilizing as the liquid plasticizer a concentrated orsaturated aqueous solution of the matrix mixture or selected mixturecomponents and the plasticizer is added to the melting zone of anextruder. In another preferred embodiment, a concentrated aqueoussolution of calcium salt being in the hydrated form is used as theplasticizer for interaction with calcium reactive polymers.

[0038] The encapsulate is continuously added in a liquid phase,following the melting of the carbohydrate matrix, by injection underpressure and mixing before exiting the extruder die.

[0039] In another embodiment, the present method employs a venting stepof the volatile plasticizer following the melt to reduce the moisturecontent to below 10% moisture in the final product.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] A more complete appreciation of the invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

[0041]FIG. 1 illustrates the effect of milling on the physical state ofa citric acid-sodium citrate buffer mixture.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] As noted above, the present invention has been made possible, inpart, by the inventor's discovery that it is possible to preparecarbohydrate-based glassy matrices, which have a sufficiently high T_(g)such that the glassy matrix is stable at ambient temperatures, with useof aqueous plasticizer. Thus, the inventors have discovered that withuse of aqueous plasticizer it is possible to prepare a maltodextrin- ormodified starch-based glassy matrix which does not undergo plastic flowor caking at ambient temperatures. This discovery is a surprising resultconsidering the well-known, large glass-transition-lowering effect ofwater in carbohydrate systems. Accordingly, before the presentinvention, one skilled in the art would not have expected that a stableglassy carbohydrate- or maltodextrin-based matrix could have beenpractically prepared using an aqueous plasticizer.

[0043] In one embodiment, the present invention relates to active agentencapsulation compositions in which (A) an encapsulate is encapsulatedin (B) a glassy matrix comprising:

[0044] (a) 95 to 100 wt. % of a maltodextrin having 5-15 D.E.; or

[0045] (b) 45 to 65 wt. % of a maltodextrin having 5 to 15 D.E. and 35to 55 wt. % of a corn syrup solid having 24 to 42 D.E.;

[0046] (c) 80 to 95 wt. % of a maltodextrin having 5 to 15 D.E., 1 to 15wt. % of a soluble or meltable salt of an organic acid, and 0 to 15 wt.% of an organic acid; or

[0047] (d) 25 to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2 to 45wt. % of a food polymer, and 10 to 30 wt. % of a mono- or disaccharideor corn syrup solids having 24 to 42 D.E.; or

[0048] (e) 45 to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2 to 22wt. % of a carbohydrate polymer having carboxylate or sulfate sidegroups, 5 to 30 wt. % of corn syrup solids having 24 to 42 D.E., and 0.2to 2.0 wt. % of a soluble calcium salt; or

[0049] (f) 30 to 100 wt. % of a modified starch (e.g. sodium octenylsuccinate modified starch), and 0 to 70 wt. % of a mono- ordisaccharide; or

[0050] (g) 85 to 100 wt. % of a modified starch (e.g. sodium octenylsuccinate modified starch), and 0 to 15 wt. % of a polyhydric alcohol.

[0051] The term encapsulate, as used in the present invention, includesagents such as medications, pesticides, preservatives, vitamins,flavoring agents, perfumery chemicals and fragrances, and food colorantsboth synthetic and natural. Suitable medications include antacids,anti-inflammatory substances, coronary vasodilators, cerebralvasodilators, peripheral vasodilators, anti-infectives, psychotopics,antimanics, stimulants, antihistamines, laxatives, decongestants,vitamins, gastrointestinal sedatives, antidiarrheal preparations,antianginal drugs, antiarrhythmics, antihypertensive drugs,vasoconstrictors, migraine treatments, anticoagulants, antithromboticdrugs, analgesics, antipyretics, hypnotics, sedatives, antiemetics,antinauseants, anticonvulsants, neuromuscular drugs, hyper- andhypo-glycaemic agents, thyroid and antithyroid preparations, diuretics,antispasmodics, uterine relaxants, mineral and nutritional additives,antiobesity drugs, anabolic drugs, erythropoietic drugs, antiasthmatics,expectorants, cough suppressants, mucolytics, antiuricemic drugs andother drug substances such as topical analgesics, local anesthetics andthe like.

[0052] Suitable pesticides include insecticides, nematocides,fungicides, herbicides, and microbicides. Insecticides, which may beencapsulated in the present compositions include those disclosed inKirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed., vol. 13,Wiley, N.Y., pp. 413-485 (1981), which is incorporated herein byreference. Suitable nematocides include, e.g., methylN′,N′-dimethyl-N-[(methylcarbamoyl)oxy]-1-thiooxamimidate (oxamyl) andthose disclosed in Kirk-Othmer, Encyclopedia of Chemical Technology, 3rdEd., vol. 18, Wiley, N.Y., pp. 305-8 (1982), which is incorporatedherein by reference. Suitable fungicides include those disclosed inKirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed. vol. 11,Wiley, N.Y., pp. 490-498 (1980), which is incorporated herein byreference. Suitable herbicides include those disclosed in Kirk-Othmer,Encyclopedia of Chemical Technology, 3rd Ed., vol. 12, Wiley, N.Y., pp.297-351 (1980), which is incorporated herein by reference. Suitableantibiotics and antimicrobials include those disclosed in Kirk-Othmer,Encyclopedia of Chemical Technology, 4th Ed., vol. 2, Wiley, N.Y., pp.854-1018 (1992) and vol. 3, pp. 1-346 (1992), both of which areincorporated herein by reference. Suitable vitamins include thosedisclosed in Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed.vol. 24, Wiley, N.Y., pp. 1-277 (1984), which is incorporated herein byreference. Suitable food additives, in addition to flavoring agents,include those disclosed in Kirk-Othmer, Encyclopedia of ChemicalTechnology, 3rd Ed., vol. 11, Wiley, N.Y., pp. 146-163 (1980), which isincorporated herein by reference.

[0053] The term flavoring agent includes spice oleoresins derived fromallspice, basil, capsicum, cinnamon, cloves, cumin, dill, garlic,marjoram, nutmeg, paprika, black pepper, rosemary and tumeric; essentialoils: anise oil, caraway oil, clove oil, eucalyptus oil, fennel oil,garlic oil, ginger oil, peppermint oil, onion oil, pepper oil, rosemaryoil, spearmint oil; citrus oils: orange oil, lemon oil, bitter orangeoil and tangerine oil; alliaceous flavors: garlic, leek, chive, andonion; botanical extracts: arnica flower extract, chamomile flowerextract, hops extract, and marigold extract; botanical flavor extracts:blackberry, chicory root, cocoa, coffee, kola, licorice root, rose hips,sarsaparilla root, sassafras bark, tamarind and vanilla extracts;protein hydrolysates: hydrolyzed vegetable protein (HVP's), meat proteinhydrolyzates, milk protein hydrolyzates; and compounded flavors bothnatural and artificial including those disclosed in S. Heath, SourceBook of Flavors, Avi Publishing Co., Westport, Conn., 1981, pp. 149-277.Representative flavor compounds are for example: benzaldehyde, diacetyl(2,3-butanedione), vanillin, ethyl vanillin and citral(3,7-dimethyl-2,6-octadienal). The flavoring agent may be in the form ofan oil, aqueous solution, non-aqueous solution or an emulsion. Flavoressences, i.e. the water soluble fraction derived from fruit or citruscan be utilized although at lower levels than the ingredients referencedabove. As will be described more fully below, the present invention isparticularly advantageous when the flavoring agent is itself a volatilecompound or is a mixture comprising a number of volatile compounds withvarying vapor pressures at ambient conditions.

[0054] When the encapsulate is lipophilic, the encapsulate is dispersedin the glassy matrix of the final product usually with the aid of anemulsifier added to the lipophilic phase or in the matrix mixture. Incontrast, when the encapsulate is hydrophilic or water-soluble, thefinal product contains the encapsulate as a dissolved solute and/or as adispersed encapsulant.

[0055] Although the exact amount of encapsulate encapsulated in thematrix will depend, in part, on the precise nature of the matrix, theidentity of the encapsulate, and the anticipated end use of the finalcomposition, the encapsulation compositions of the present inventionwill typically comprise 2.5 to 15 wt. % of encapsulate, based on thetotal weight of the encapsulation composition. Preferably, the presentencapsulation compositions will comprise 7 to 12 wt. % of encapsulate,based on the total weight of the composition. It is preferred that theencapsulate is a flavoring agent.

[0056] In addition to the foregoing encapsulates, various optionalingredients such as are conventionally used in the art, may be employedin the matrix of this invention. For example, colorings, sweeteners,fragrances, diluents, fillers, preservatives, anti-oxidants,stabilizers, lubricants, and the like may be employed herein if desired.

[0057] As noted above, the encapsulate is encapsulated in a glassymatrix of one of (a), (b), (c), (d), (e), (f), or (g). In all of thedefinitions of matrices (a), (b), (c), (d), (e), (f) and (g), all wt. %values are based on the total weight of the glassy matrix (B).

[0058] In one embodiment, the glass matrix comprises (a) 95 to 100 wt. %of a maltodextrin having 5-15 D.E. Preferably, in embodiment (a), theglass matrix comprises 95 to 97 wt. % of a maltodextrin having 5-15 D.E.

[0059] The relationship between the glass transition temperature andmoisture content for a maltodextrin matrix has been described by Y. Roosand M. Karel, J. Food Science, Vol. 56(6), 1676-1681 (1991), which isincorporated herein by reference. T_(g), the glass transitiontemperature, increases with decreasing moisture content or increasingmolecular weight of the maltodextrin. The experimental procedure for theglass formation described by Roos and Karel in this reference is notamenable to commercial application. Also noteworthy is that the systemdescribed in this reference, maltodextrin solids and moisture, does notinclude organic flavor solutes. Incorporation of water-soluble lowmolecular weight compounds contributed by most flavors would act as aplasticizer in such a matrix.

[0060] Commercial maltodextrins are usually prepared from hydrolysis ofa selected corn starch. The resulting maltodextrin products are obtainedas complex mixtures of carbohydrate oligomers which also contain minoramounts of mono- and disaccharides. Any commercial maltodextrin with adextrose equivalent (D.E.) of 5 to 15 may be suitably utilized. However,maltodextrins with 10 to 15 D.E. are preferred. The term dextroseequivalent (D.E.) as used in the present specification refers to thepercentage of reducing sugars (dry basis) in a product calculated asdextrose. Good results have been achieved using Lodex 10 of AmericanMaize Company (Hammond, Ind.). Other commercial maltodextrin-likematerials obtained from rice, wheat, and tapioca starches as well asagglomerated forms of maltodextrins such as the Penwest Food Product,Soludex, are also suitable.

[0061] Although the matrix of embodiment (a) is described as comprising95 to 100 wt. % of a maltodextrin having 5 to 15 D.E., it should beunderstood that such material as commercially supplied contains 4 to 7wt. % of moisture and that this water content is implicit in the term“maltodextrin” as used above. In addition, water is also introduced intothe final matrix by the use of the present aqueous plasticizers.Similarly, many of the starting materials in embodiments (b), (c), (d),(e), (f), and (g) will also contain moisture as commercially supplied,and water will also be introduced into the final matrix composition byuse of the present aqueous plasticizers.

[0062] Accordingly, it is to be understood that in all of thedefinitions for embodiments (a), (b), (c), (d), (e), (f), and (g) of theglassy matrix, the relative amounts of the various components areexpressed on the basis of the relative amounts of each component used asreceived from the commercial supplier. In other words, although thecomponents of the glassy matrices are used as received from the supplierand thus contain some moisture, the relative amounts of the componentsin the glassy matrices are expressed as if the commercially suppliedcomponents were completely moisture-free. It should be furtherunderstood that, although the final glassy matrix may contain water, thewater content is not expressly stated.

[0063] The amount of water permissible in the final glass matrix isfunctionally limited by the desired T_(g) of the glass matrix. Thus, theglass matrix will suitably contain water in an amount less than thatwhich would lower the T_(g) below 35° C. Preferably, the glass matrixwill contain water in an amount less than that which would lower theT_(g) of the matrix below 40° C. Although the exact upper limit on theamount of water will depend on the identity of the component ingredientsof the glassy matrix, typically the amount of water present will be 5 to10 wt. %, based on the total weight of the glassy matrix, preferably 5to 9 wt. %, based on the total weight of the glassy matrix.

[0064] When, in embodiment (a), the matrix comprises less than 100 wt. %maltodextrin (water implicit), then the balance of the matrix maycomprise up to 5 wt. % of any component which does not adversely effecteither the matrix or the encapsulate. Lower molecular weightcarbohydrates, such as glucose, sucrose, maltose, and 24 to 42 D.E. cornsyrup solids, yield more easily processed matrices when added asadditional components. Other processing aids in the form of extrusion“slip agents” are food emulsifiers, which can combine the concomitantfunction of processing aid and surfactant, include the distilledmonoglycerides of fatty acids, distilled propylene glycol monoesters offatty acids, distilled succinylated monoglycerides of fatty acids suchas the Myverol product series available from Eastman Chemicals Co.;sorbitan fatty acid esters, polyoxyethylene(s) sorbitan monoesters offatty acids; distilled acetylated monoglycerides of fatty acids,mono-diglycerides of fatty acids and fats and oils from food lipidsources. These may be added in amounts of 0.25 to 2.5 wt. %.

[0065] When the matrix is (a), the liquid plasticizer may be water.Alternatively, maltodextrin melts can also be facilitated by use of aplasticizing agent prepared as an aqueous maltodextrin solution. Theadvantage of this latter procedure is to insure adequate hydration andrapid dispersion of liquid plasticizer into the dry mixture in anextruder. A maltodextrin solution having any concentration up tosupersaturation can be employed as the liquid plasticizer in thisprocedure. Similarly, water-flavoring agent solutions and water-alcoholflavoring agent mixtures, such as vanilla extracts can bepreconcentrated with solids from the dry maltodextrin base to yield asyrup which may be used as the liquid plasticizer.

[0066] When a plasticizing system consisting of a 50% [w/w] aqueoussolution of Lodex-10 as obtained from the supplier, was employed in anamount of 0.9 lb with 16.9 lb of Lodex 10, the resultant matrix obtainedhad a water content of 9.8 wt. % (by Karl Fisher method) and a T_(g) of44° C.

[0067] In embodiment (b), the glassy matrix comprises 45 to 65 wt. % ofa maltodextrin having 5 to 15 D.E., preferably 48 to 62 wt. % of amaltodextrin having 5 to 15 D.E., and 35 to 55 wt. % of a corn syrupsolid having 24 to 42 D.E., preferably 38 to 52 wt. % of a corn syrupsolid having 24 to 42 D.E. The same types of maltodextrins utilized inembodiment (a) are suitably used in embodiment (b). Thus, themaltodextrins used in embodiment (b) preferably have 10 to 15 D.E.

[0068] When the encapsulate to be encapsulated is pH sensitive, it ispreferred that the glassy matrix comprise (c). Many pure compounds andflavorings systems are pH sensitive. It is well known that heating offood carbohydrate polymers in the amorphous form in the presence ofacidic or basic agents will lead to carmelizaton and result inoff-flavor development and color formation. Moreover, the presence oflow molecular weight acids can be detrimental to flavors present duringthe melt encapsulation process.

[0069] When the matrix is (c), it comprises 80 to 95 wt. % of amaltodextrin having 5 to 15 D.E., 1 to 15 wt. % of a soluble or meltablesalt of an organic acid, and 0 to 15 wt. % of an organic acid, drybasis. The matrix, in embodiment (b), preferably comprises 80 to 90 wt.% of a maltodextrin having 10 to 15 D.E., 1 to 14 wt. % of a soluble ormeltable salt of an organic acid, and 0 to 13 wt. % of an organic acid,dry basis. The same types of maltodextrins which are suitable for use inembodiment (a) are also suitable for embodiment (c). Further, asdescribed above with reference to embodiment (a), it should beunderstood that the maltodextrin used in embodiment (c) will typicallycontain 5 to 8 wt. % of moisture as received from the commercialsupplier and that moisture will also be introduced into the final matrixby the use of the present aqueous plasticizers.

[0070] Suitable organic acids include those such as citric, malic,adipic, cinnamic, fumaric, maleic, succinic, and tartaric acid, and themono-, di-, or tribasic salts of these acids are suitable organic acidsalts. Suitable salts of these acids are the soluble or meltable saltsand include those salts in which one or more acidic protons are replacedwith a cation such as sodium, potassium, calcium, magnesium, andammonium. Preferred salts include the sodium and potassium salts ofcitric acid.

[0071] The buffer is suitably prepared having a ratio of acid totrisodium acid salt of 10:1 to 1:4, preferably 4:1 to 1:2; or an acid todisodium salt ratio of 10:1 to 1:6, preferably 3:1 to 1:3; or an acid tomonosodium acid salt ratio of 10:1 to 1:10, preferably 2:1 to 1:2. Mixedbuffers can be prepared in which the acid and acid salt are fromdifferent acids.

[0072] When the acid and/or acid salt exist in a high meltingcrystalline form, then the addition of moisture may not plasticize ormelt the acid-acid salt rapidly in the mixture with the maltodextrin.Furthermore, addition of excess water, in this case, would result in alowering of the T_(g) of the resulting matrix to an undesirable level.Accordingly, in such cases it is preferred to co-mill the acid/acid saltmixture prior to mixing with the maltodextrin. It has been found thatco-milling the acid/acid salt mixture generates an amorphous binarysolid solution. This binary solid may then be mixed with desired ternarycomponent such as a maltodextrin and the mixture melt-extruded.

[0073] The co-milling of the acid/acid salt mixture may be carried outin any conventional milling apparatus such as ball mills and centrifugalimpact mills. Typically the acid and acid salt are combined in theproportions to be used in the matrix and milled. A single pass through aBrinkmann laboratory impact mill fitted with 0.5 mm screen is adequateto convert all the crystalline phases of a citric acid-trisodium citratemixture into the amorphous, non-crystalline state as determined by DSC.

[0074]FIG. 1 shows the effect of milling on the physical state of thecitric acid-sodium citrate buffer mixture as evidenced by DSC thermalanalyses. Curve 1 (-) represents the thermogram of an unprocessedmixture. Two melt transitions are evidenced corresponding to the meltingof the acid and acid salt respectively. Curve 2 (---) represents theidentical mixture after a single pass through a Brinkmann impact mill.The amorphous character is noted by a change in baseline correspondingto the 60-100° C. region. The exotherm centered at approximately 120° C.indicates recrystallization of an amorphous component(s). Finally, atthe higher temperature region of the scan, the crystalline phasesundergo a melt transition. This amorphous mixture will ultimately returnto the more stable crystalline state, i.e., samples made as describedabove exhibit only melt transitions after 10 days at ambienttemperature. The benefit in the use of the amorphous acid-acid saltingredient is increased speed and ease of solution into the maltodextrinmelt.

[0075] In another embodiment, the matrix is (d), a mixture comprising 25to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2 to 45 wt. % of afood polymer, and 10 to 30 wt. % of a mono- or disaccharide or cornsyrup solids having 24 to 42 D.E., dry basis. Preferably in embodiment(d), the matrix comprises 45 to 70 wt. % of a maltodextrin having 10 to15 D.E., 5 to 20 wt. % of a food polymer, and 25 to 30 wt. % of a mono-or disaccharide or corn syrup solids having 24 to 42 D.E.

[0076] Examples of suitable food polymers include methyl cellulose,hydroxypropyl methyl cellulose, high methoxypectin, gum arabic (acacia),locust bean gum, guar gum; the lesser utilized natural gums such as gumghatti, gum tragacanth, gum karaya; proteins such as gelatin orα-casein; microbial gums such as xanthan, or gellan; pregelatinizedstarches in addition to carbohydrate polymers such as inulins,beta-glucans and konjac flour. Methyl cellulose and hydroxypropyl methylcellulose are preferred.

[0077] For some of the compounds used as the food polymer in embodiment(d), the molecular weight is essentially controlled by the source and,in fact, may not be precisely known. For example, the gums listed aboveare not characterized or described by those of skill in the art in termsof molecular weight. Instead, such gums are fully characterized byidentification of their source. Thus, e.g., the term “gum arabic” fullyand completely defines a particular composition and no furthercharacterization is required.

[0078] In contrast, the molecular weight of a cellulose ether, such asmethyl cellulose or hydroxypropyl methyl cellulose, is generallyexpressed in terms of the viscosity at 20° C. of an aqueous solutioncontaining 2 wt. % of the cellulose ether. Suitable cellulose ethers foruse in embodiment (d) are those having a viscosity of 3 to 100,000centipoises, preferably 4000 to 15,000 centipoises. Cellulose ethers arealso characterized in terms of the degree of hydroxypropoxyl andmethoxyl substitution. The term “methoxy degree of substitution” (MDS)refers to the average number of methyl ether groups present peranhydroglucose unit of the cellulose molecule. The term “hydroxypropoxylmolar substitution” (HPMS) refers to the average number of moles ofpropylene oxide which are reacted with each anhydroglucose unit of thecellulose molecule. In embodiment (d), the methyl cellulose suitably hasa MDS of from 19 to 31, preferably 27 to 31. The hydroxypropyl methylcellulose suitably has a MDS of from 19 to 30, preferably 24 to 30, anda HPMS of from 4 to 12, preferably 7 to 12.

[0079] Gelatin is not usually characterized in terms of molecular weightbut instead is characterized in terms of “Bloom” or jelly strength asmeasured with a Bloom Gelometer. In embodiment (d), suitable gelatinsare those having a Bloom of 50 to 300, preferably 100 to 300. Both TypeA and Type B gelatin may be used.

[0080] The same types of maltodextrins described as being suitable forembodiments (a), (b), and (c) are also suitable for embodiment (d).Preferably the maltodextrin has 10 to 15 D.E. in embodiment (d).

[0081] Mono- and disaccharides suitable for use in embodiment (d)include glucose, fructose, galactose, ribose, xylose, sucrose, maltose,lactose, cellobiose, and trehalose; polyols, e.g., glycerin andpropylene glycol; as well as corn syrup solids, high fructose cornsyrups, high maltose corn syrups and hydrogenated corn syrups. Preferredare glucose and maltose. Corn syrup solids having 24 to 42 D.E. are alsopreferred.

[0082] Glass matrices prepared from low molecular weight components suchas monosaccharides, disaccharides, corn syrup solids and maltodextrinsare stable at ambient conditions if the glass exhibits a T_(g) of >30°C. However, release of solutes is relatively rapid when placed inaqueous media. A common method for controlled release in thepharmaceutical industry employs direct compression of tablets preparedwith methyl cellulose and hydroxypropyl methyl cellulose in variouscombinations from 98% to less than 26% of modified celluloses. Theprocedures employ dry blending of all components followed by a wet ordry tableting process. These teachings are described in part in thetechnical brochure “Formulating for Controlled Release with METHOCELPremium Cellulose Ethers” Dow Chemical Company, Midland, Mich., 1987,but are not directly applicable to volatile and liquid agents as desiredby the food industry.

[0083] It has now been found that modified cellulose ethers such asmethyl cellulose [Methocel A; Dow Chemical Co.], hydroxypropyl methylcellulose [Methocel E,F,J,K; Dow Chemical Co.], when combined with amaltodextrin or maltodextrin-sugar solids base, yield glassy matriceswith increased T_(g), which are suitable for the encapsulation ofvolatile flavorings and flavor compounds. In addition, the modifiedcellulose polymer rehydrates to develop increased viscosity of thematrix and slow the diffusion of the solute agents into the aqueousmedia, upon hydration in application, i.e., from extraneous water incontact with the glass-flavor matrix.

[0084] An exemplary series of methyl cellulose/hydroxypropyl methylcellulose mixtures were prepared and are shown below. The mixtures havethe composition ranges of: a] Methyl cellulose [Dow, Methocel A4M]  2 to45 wt. % b] Maltodextrin [American Maize, Lodex-10] 20 to 80 wt. % c]Corn syrup solids [American Maize, Frodex 42] 20 to 30 wt. %

[0085] More preferably the composition was made of the components in therange: a] Methyl cellulose [Dow, Methocel A4M]  4 to 25 wt. % b]Maltodextrin [American Maize, Lodex-10 25 to 80 wt. % c] Corn syrupsolids [American Maize, Frodex 42] 20 to 30 wt. %

[0086] and the most preferred mixture had a composition of: a] Methylcellulose [Dow, Methocel A4M]  5 to 20 wt. % b] Maltodextrin [AmericanMaize, Lodex-10] 45 to 75 wt. % c] Corn syrup solids [American Maize,Frodex 42] 25 to 30 wt. %

[0087] Encapsulation was tested utilizing an extruder to which moisturewas added to the original dry mix at the feed port. Simultaneously withthe addition-of the water, orange oil containing selected emulsifier,was injected into the melt zone of the extruder. The added moisture islimited to addition of no more than 3 to 5 wt. % additional moisture tothe dry mix. Analysis of the encapsulating matrix shows T_(g)'s in therange of 35 to 50° C.

[0088] In another embodiment, the matrix comprises (e) 45 to 80 wt. % ofa maltodextrin having 5 to 15 D.E., 2 to 22 wt. % of a carbohydratepolymer having carboxylate or sulfate groups, 5 to 30 wt. % of cornsyrup solids having 24 to 42 D.E., and 0.2 to 2.0 wt. % of awater-soluble calcium salt, dry basis. Preferably, matrix (e) comprises40 to 80 wt. % of a maltodextrin having 10 to 15 D.E., 4 to 15 wt. % ofa carbohydrate polymer having carboxylate or sulfate groups, 10 to 25wt. % of corn syrup solids having 24 to 42 D.E., and 0.4 to 1.8 wt. % ofa water-soluble calcium salt, dry basis.

[0089] Suitable carbohydrate polymers having carboxylate or sulfategroups are water-soluble and are represented by sodium carboxymethylcellulose (CMC), low methoxy pectin(s), sodium alginate, and {kappa} and{iota} carrageenan(s).

[0090] The molecular weight of sodium carboxymethyl cellulose isgenerally expressed in terms of viscosity at 25° C. of an aqueoussolution containing 1 wt. % of the sodium carboxymethyl cellulose. Inembodiment (e), the sodium carboxymethyl cellulose suitably has aviscosity of 50 to 8000 centipoises, preferably 2000 to 8000centipoises. In addition sodium carboxymethyl cellulose may becharacterized in terms of the degree of substitution (DS) of thehydroxyl groups at carbons C-2, C-3, and C-6 of the d-glucose units.When all the hydroxyl groups are substituted the cellulose derivative issaid to have a DS of 3. In embodiment (e), the sodium carboxymethylcellulose suitably has a DS of 0.7 to 1.0, preferably 0.7 to 0.9.

[0091] Suitable low methoxy pectins are those having a degree ofesterification of 0.2 to 0.5.

[0092] Sodium alginate is commercially available from Hercules Companyunder the trade name AQUALON® and may be used directly as received. Iotacarrageenan is sold by Sigma Chemical Company under the name CarrageenanType V.

[0093] The same types of maltodextrins used in embodiments (a)-(d) mayalso be used in embodiment (e). Preferably, the maltodextrin has 10 to15 D.E. in embodiment (e). The corn syrup solid in embodiment (e)preferably has 24 to 42 D.E.

[0094] Suitable soluble calcium salts include inorganic salts such asCaCl₂ or CaHPO₄ or salts of organic acids such as calcium lactate orcalcium acetate. Less preferred is the use of calcium salts of theorganic acids in the crystalline form admixed with the dry components ofthe matrix.

[0095] The solution chemistry of food hydrocolloids containingcarboxylate groups such as the polygalacturonide polymer low methoxypectin, modified celluloses such as CMC (carboxymethyl cellulose), andthe sulfate containing {kappa} and {iota}-carrageenan is known. However,it has now been found that when these polymers become plasticized in thelow moisture environment of a carbohydrate melt, the interaction betweencarboxylate or sulfate side chain groups no longer follows the expectedteachings of the food technology as known from the fully hydratedpolymers in solution. It has now been found that to obtain the desiredresponse of increased effective molecular weight of the cross-linkedpolymer, the calcium ion is preferably in a hydrated form. This resultis achieved by use of concentrated solutions of highly soluble calciumsalts, i.e., calcium lactate and calcium chloride. The largeconcentration of hydrated calcium ion allows limited amounts ofadditional free water to be added as plasticizer. In addition, separatedliquid streams, one of saturated CaCl or calcium lactate and a second ofplasticizing aqueous media, can be metered to optimize the meltextrusion process and yield the largest T 's consistent with theoperating conditions of the extruder.

[0096] Exemplary compositions comprised of calcium sensitive foodpolymer, based upon low methoxy pectin, were prepared as a dry blend as:[a] low methoxy pectin  2 to 22 wt. % [b] maltodextrin 45 to 80 wt. %[c] corn syrup solids  5 to 30 wt. %

[0097] A more preferred formulation range is: [a] low methoxy pectin  4to 15 wt. % [b] maltodextrin 45 to 80 wt. % [c] corn syrup solids 10 to30 wt. %

[0098] and an especially preferred range is: [a] low methoxy pectin  5to 10 wt. % [b] maltodextrin 50 to 75 wt. % [c] corn syrup solids 15 to25 wt. %

[0099] The solubility of carbohydrate polymers in concentrated sugarmedia varies widely. For example those gums and hydrocolloids utilizedin the confectionery industry e.g. high methoxy pectin, gum arabic andbacterial gums such as gellan have been found to function well in themelt extrusion process. These polymers have been found to melt underconditions that did not cause interactions of the plasticizing water andlow molecular weight components to generate extremely high viscositymelts.

[0100] A series of polymers cited above were tested for meltcompatibility with the maltodextrin-sugar solids-water plasticizingcarrier. Of these tested, the high methoxy pectin and gellan worked mostefficaciously in the melt-extrusion process. The addition of thesepolymers also increased the glass T_(g).

[0101] The following formulations were utilized: [a] food polymer  5 to25 wt. % [b] maltodextrin [5-15 DE] 40 to 80 wt. % [c] mono- ordisaccharide/ 10 to 30 wt. % or corn syrup solids [24-42 D.E.]

[0102] A more preferred range would be: [a] food polymer  5 to 15 wt. %[b] maltodextrin [5-15 DE] 50 to 70 wt. % [c] mono- or disaccharide/ 10to 30 wt. % or corn syrup solids [24-42 D.E.]

[0103] The relative composition is dependent upon the ingredient form ofthe polymer. In many cases, such as with high methoxy pectin and gellan,the supplier will dilute with functional or food inert materials tostandardize the ingredient for normal commercial usage. In those cases,the above compositions are adjusted to account for the additionalingredients.

[0104] In the case of gellan, a non-diluted form of the polymer wasobtained from the supplier, Kelco. The following formulation would be arepresentative composition: [a] gellan (KELCOGEL ®)  7.0 wt. % [b]maltodextrin (Lodex-10) 61.5 wt. % [c] corn syrup solids (Frodex-42)30.0 wt. % [d] buffer (Citric Acid: NaCitrate −1:2)  1.5 wt. %

[0105] The dry ingredients ‘a’ through ‘d’ were prepared as a preblendedmixture and processed by melt extrusion with injection of orange oilunder pressure into the matrix melt. The resulting glassy matrixcontaining the encapsulated orange oil had a T_(g) of 45° C.

[0106] When the matrix is (f), the maltodextrin is replaced by amodified starch, i.e. the sodium octenyl succinate modified starch. Amixture comprising 30-100 wt. % of modified starch and the balance 0-70wt. % of mono- or disaccharide is utilized. Preferably, in embodiment(f), the matrix comprises 60 to 90 wt. % modified starch and 10 to 40wt. % mono- or disaccharide. A preferred modified starch is sold underthe trade name of CAPSUL® (National Starch Co.) which is characterizedas a sodium octenyl succinate modified starch. Similar functionalingredients are available from American Maize Company as the Amiogum 23product. Other modified starches with similar functionality include theNational Starch Purity Gum BE, 1773, and 539. Suitable mono- anddisaccharides include, e.g., glucose, sucrose, lactose, fructose, andmaltose. Preferred are glucose, sucrose, and maltose.

[0107] When the matrix is (g), the modified starch is utilized with aplasticizer consisting of polyhydric alcohol or polyhydric alcohol-watermixtures added in a liquid feed to the base. The functional mixture thencomprises 85 to 100 wt. % modified starch and 0 to 15 wt. % polyhydricalcohol. Preferably in embodiment (g) the matrix comprises 85 to 95% wt.% modified starch and 5 to 15 wt. % polyhydric alcohol. The samemodified starches used in embodiment (f) may be used in embodiment (g).Suitable polyhydric alcohols include propylene glycol and glycerin.

[0108] The encapsulation compositions of the present invention may beprepared by a process involving: (i) mixing (a), (b), (c), (d), (e),(f), or (g) with a liquid plasticizer and an encapsulate in an extruder,to obtain a melted matrix; and (ii) extruding said melted matrix.

[0109] The present process may be carried out in a conventional singlescrew or co-rotating twin screw extruder. The choice of using a singleor twin screw extruder will depend on a number of factors but mainly onthe conveying properties of the matrix and the encapsulate. A singlescrew extruder is completely dependent on drag flow, while a twin-screwextruder provides some degree of positive pumping action.

[0110] In general, whenever a single screw extruder may be used, it maybe replaced with a twin screw extruder. However, there are circumstanceswhen a single screw extruder may not be used and a twin screw extruderis required. Such circumstances include situations when a glassy matrixwith a high T_(g) is being prepared and a low amount of aqueousplasticizer is added. In this case, use of a single screw extruder mayresult in caramelization of the matrix starting materials and cloggingof the single screw extruder.

[0111] In the preparation of the present glassy matrices, the drycarbohydrate and any noncarbohydrate components are mixed with anaqueous plasticizer. The carbohydrate and other matrix components arereferred as “dry”, but, as discussed above, many of these componentswill actually contain moisture as received from the commercial supplier.In the present process, the matrix components may be used as received.

[0112] The aqueous plasticizer may be water, an aqueous solution orsuspension of one of the matrix components (e.g, an aqueous solution ofa maltodextrin), an aqueous solution or suspension of an active agent,an oil-in-water emulsion, an alcohol-water solution or suspension of anactive agent (e.g., vanilla extract), an aqueous solution or suspensionof an organic acid or salt of an organic acid, or an aqueous solution orsuspension of a calcium salt. When the matrix is (a) or (b), it ispreferred that the plasticizer is an aqueous solution or suspension ofthe maltodextrin. When the matrix is (c), it is preferred that theplasticizer is an aqueous solution or suspension of one or more of (i)the maltodextrin or (ii) the organic acid and/or salt of the organicacid. When the matrix is (d), it is preferred that the plasticizer is anaqueous solution or suspension of one or more of (i) the food polymer,(ii) the maltodextrin, or (iii) the mono- or disaccharide or the cornsyrup solids. When the matrix is (e), it is preferred that theplasticizer is an aqueous solution or suspension of one or more of (i)the maltodextrin, (ii) the corn syrup solids, and (iii) the calcium saltor compatible constituents selected from (i), (ii), and (iii). When thematrix is (f), it is preferred that the plasticizer is an aqueoussolution or suspension of (i) the monosaccharide, (ii) the disaccharide,or (iii) a mixture of mono- and disaccharide. When the matrix is (g), itis preferred that the plasticizer is an aqueous solution of the polyol.

[0113] The exact amount of aqueous plasticizer mixed with the dry matrixcomponents will depend, in part, on the amount of moisture present inthe dry matrix components as received from the supplier, theplasticizing effect, if any, of the active agent, and the T_(g) desiredfor the final matrix. Usually the amount of plasticizer to be added isdetermined by first deciding what range of T_(g) is desired and thenexperimentally determining how much aqueous plasticizer can be addedwhile still achieving the desired T_(g). T_(g) (glass transitiontemperature) values were obtained by Differential Scanning Calorimetry(DSC) using a Mettler Thermal Analysis system employing a D-20calorimeter cell and reported as the temperature at the mid-point of theglass transition. In general, an increase in the moisture content of thefinal matrix of any given composition of the present invention will leadto a decrease in the T_(g) of the final matrix. Further, generallyspeaking, decreasing the total amount of water in the starting materialswill decrease the water content of the final composition. By using thesegeneral relationships and the teachings of the present specification oneof skill in the art can easily determine the proper amount ofplasticizer to be added in order to prepare the present glassy matrices.

[0114] Thus, e.g., the starting materials will be utilized as received;the melt process is initiated by addition of excess moisture in the formof an aqueous liquid consisting of pure water or aqueous solute solutioninto the feed port of the extruder. Upon reaching an initial temperatureand material flow equilibration, the aqueous feed is reduced until theresulting exudate matrix is obtained which upon cooling is determined tobe in the glassy state. With experience using specified matrices, theminimum feed rate for the aqueous component can be set initially and theprocess run to yield the glassy matrix immediately.

[0115] The present encapsulation compositions are stable at ambienttemperatures and, thus, have a T_(g) of at least 35° C. Preferably, thepresent encapsulation compositions have a T_(g) of at least 40° C. Thus,the glassy matrix of the present compositions will typically contain 3to 10 wt. % of water, preferably 5 to 9 wt. % of water.

[0116] As noted above, the dry components of the matrix and the aqueousplasticizer are mixed in the heating zone of an extruder. Thetemperature to which the heating zone is heated will depend on theidentity of the matrix material and the amount of plasticizer added.Typically, the heating zone will be heated to a temperature of 194 to320° F., preferably 230 to 284° F.

[0117] After the plasticizer and dry matrix components have been mixedand melted, the resulting melted matrix is mixed with the active agent.This mixing is conveniently carried out in a separate extruder zone,downstream of the heating zone. Alternatively, in the case of athermally stable active agent, the active agent may comprise onecomponent of the aqueous plasticizer or otherwise be mixed with theaqueous plasticizer and dry matrix components in the heating zone of theextruder.

[0118] The proportion of encapsulate added will generally equal theproportion of encapsulate in the final composition. Thus, typically, theamount of encapsulate to be added will be determined by the amount ofencapsulate desired in the final composition.

[0119] In the case of volatile encapsulates (such as diacetyl), someloss of encapsulate may occur by volatilization, when the hot melt exitsthe extruder. In these cases, the amount of encapsulate in the finalcomposition may be controlled by adding excess encapsulate to the meltedmatrix to compensate for the loss due to volatilization.

[0120] In some cases, it may be necessary to add an amount of water tothe dry matrix components which would ordinarily result in the amount ofwater in the final matrix being so great that the final composition hasa lower T_(g) than desired. Such instances may arise when the drycomponents are slowly hydrated, and the initial water content must behigh to prevent decomposition of the dry matrix components in themelting zone of the extruder. In these cases, the amount of water in thefinal composition may be lowered to the required level by venting themelted matrix. Venting procedures and suitable apparatus are disclosedin U.S. patent application Ser. No. 07/948,437, which is incorporatedherein by reference. In the case of a nonvolatile active agent, theventing may take place either before or after the mixing of theencapsulate with the melted matrix. In the case of a volatile activeagent, the venting is preferably carried out before the mixing of theencapsulate with the melted matrix.

[0121] The final extruded composition may be used as extruded, that is,in the form of an extruded rod or filament. Alternatively, the extrudedmaterial may be further processed, preferably after cooling, by, e.g.,grinding, pulverizing, etc. The ground composition may be used as is forthe storage and/or sustained release of the encapsulate or it may bewashed of surface oils in the case of dispersed encapsulate with foodgrade solvents such as ethanol, isopropanol, hexane and the residualsolvent removed by standard processes.

[0122] The present encapsulation compositions are particularly usefulfor the encapsulation and long-term storage of flavoring agents. Thepresent compositions permit the long-term storage of sensitive and/orvolatile flavors. The compositions may be added directly to foodpreparations and offer the added benefit of being easily metered. Inaddition, the matrix components contribute little to the flavor and/oraroma of a food prepared from the present compositions.

[0123] Having generally described this invention, a furtherunderstanding can be obtained by reference to certain specific exampleswhich are provided herein for purposes of illustration only and are notintended to be limiting unless otherwise specified.

EXAMPLES Example 1

[0124] A carbohydrate base consisting of a 10 D.E. maltodextrin[Lodex-10, American Maize Company] was fed at a rate of 15 lbs/hr into atwin screw extruder. The jacket temperature was set to 250° F. by meansof a circulating hot oil heater. Water plasticizer was added to theentry port at a rate of 7 mls/min. The encapsulate, diacetyl [AldrichChemical Co.], was injected into the molten mixture through a jacketport using a piston metering pump at a rate of 12 mls/minute. Theexudate composed of the diacetyl-maltodextrin melt was then delivered at200° F. through a discharge nozzle and collected at ambient pressure.Upon passive cooling, the solid, yellow matrix was characterized bydifferential scanning calorimetry (DSC) as a glass with a T_(g) of 50°C. The product contained 4.9 wt % diacetyl and 8.3 wt. % moisture (byKarl Fisher analysis). Following storage of the bulk sample at ambientconditions for 4 months, the diacetyl content was analyzed at 4.0 wt. %(82% retention).

Example 2

[0125] A carbohydrate base consisting of a 10 D.E. maltodextrin (Lodex10, American Maize Company) was fed at a rate of 15 lbs/hr into anextruder as described in Example 1. A fluid plasticizer consisting of a50% (w/w) aqueous 10 D.E. maltodextrin solution was added to the feedport at a rate of 14 ml/min. The extruder was maintained at a jackettemperature of 250° F. Prechilled diacetyl [Aldrich Chemical Co.] wasinjected into the molten matrix through an injection port using a pistonmetering pump at a rate of approximately 12 mls/minute. The encapsulatemixture composed of the diacetyl-maltodextrin melt was delivered througha discharge nozzle and collected at ambient pressure as an expandedmaterial which rapidly collapsed to yield a translucent yellow solid.The resultant solid was characterized by DSC as a glass with a T_(g) of51° C. The matrix contained 4.4 wt. % diacetyl and 7.6 wt. % moisture(by Karl Fisher analysis). Following storage of the bulk sample atambient conditions for 4 months, the diacetyl content was analyzed at4.0 wt. % (90% retention).

Example 3

[0126] A buffered base composition was prepared as a dry blend with thefollowing components.

[0127] 80 wt. % of 10 D.E. Maltodextrin [Lodex 10, American Maize Co.]

[0128] 10 wt. % of Citric Acid [Cargill]

[0129] 10 wt. % of Sodium Citrate [Na₃Citrate.H₂O, Pfizer]

[0130] The base mixture was fed at the rate of 15 lb/hr. into anextruder as described in Example 1. Water is added to the feed port at 3ml/min. Prechilled diacetyl was injected into the molten mixture througha jacket port in the extruder using a positive displacement pump at arate of approximately 8 ml/minute. The molten exudate composed of thebuffered diacetyl-maltodextrin melt was then delivered through adischarge nozzle at 227° F. and collected at ambient pressure. Uponcooling, the matrix was characterized by DSC as a glass with a T_(g) of41° C., at a moisture level of 7.3 wt. % (by Karl Fisher analysis). Theencapsulated flavoring was determined to be 3.0 wt % of acetyl.

[0131] The practical utility of buffered melts is best illustrated whenacid or base sensitive agents are encapsulated. In a separateexperimental study the flavoring compound, diacetyl, was encapsulatedusing the composition of sample 4 in Table I with the twin screwextruder. The melt was obtained as a dark brown solid showing the basecatalyzed destruction of the alpha-dione compound. TABLE I Matrix-Buffer pH Responses Sample Matrix Composition Wt % Prepared Mixture pHMelt pH 1 Lodex-10 90 this 3.97 3.77 Na₃Citrate  5 application CitricAcid  5 2 Lodex-10 80 U.S. Pat. No. 2.40 2.32 4,820,534 Citric Acid 20 3Lodex 10 80 Example 3 3.82 3.88 Citric Acid 10 this Na₃Citrate 10application 4 Lodex-10 75 this 7.49 7.44 Frodex 42 15 applicationNa₃Citrate 10

Example 4

[0132] A matrix composition containing a food polymer was prepared withthe following components:

[0133] 61.0 wt. % of 10 D.E. Maltodextrin [Lodex 10, American Maize Co.]

[0134] 30.5 wt. % of 42 D.E. Corn Syrup Solids [Frodex-42, AmericanMaize Co.]

[0135] 7.0 wt. % of Gellan CF [KELCOGEL®, Kelco Co.]

[0136] 0.5 wt. % of Citric Acid [Cargill]

[0137] 1.0 wt. % of Na₃Citrate.2H₂O [Pfizer]

[0138] The mixture was fed into a dual extruder system in which theinitial melt is obtained by feeding 15 lbs/hr of the base mix into thefirst extruder with a jacket heated to 300° F. Water is added to thefeed port at the rate of 27 mls/min to yield a molten, plastic mass.This melt was discharged with venting of moisture as steam at 268° F.into a second extruder with the jacket temperature at 300° F. A flavorload consisting of 90 parts orange oil [Citrus and Allied] in which isdissolved 10 parts polyglycerol ester emulsifier [Caprol 3G0, WitcoChemical Co.] was prepared and injected through a jacket port in thesecond extruder using a metering pump at a rate of 10 mls/min. Theproduct collected from the discharge outlet of the second extruder unitwas obtained as a hot, plastic mass which upon cooling set into a hard,fracturable solid. The resultant solid was characterized by DSC as aglass with a T_(g) of 41° C., at a moisture level of 6.8 wt. % (by KarlFisher analysis). The encapsulated flavoring was determined to be 2.9 wt% of citrus oil.

Example 5

[0139] A carbohydrate base matrix containing a functional polymer wasprepared as a mixture consisting of:

[0140] 72.5 wt. % 10.D.E. Maltodextrin [Lodex-10, American Maize Co.]

[0141] 20.0 wt. % 42 D.E. Corn Syrup Solids [Frodex-42, American MaizeCo.]

[0142] 7.5 wt. % Methyl Cellulose [Methocel A4M, Dow Chemical Co.]

[0143] The components were dry blended as obtained. The processdescribed in Example 1 was utilized. Water was delivered into thefeed/port at 7 ml/min., and orange oil [Citrus and Allied] was injectedat 12 ml/min. The encapsulated orange oil was retained at 8.3 wt. %, andthe matrix was analyzed at 8.9 wt. % moisture (by Karl Fisher Analysis).The solid was characterized by DSC as a glass with a T_(g) of 40° C.

Example 6

[0144] A matrix composition was prepared with the following components:

[0145] 70.0 wt. % of 10 D.E. Maltodextrin [Lodex 10, American Maize Co.]

[0146] 20.0 wt. % of 42 D.E.Corn Syrup Solids [Frodex-42, American MaizeCo.]

[0147] 10.0 wt. % of Low Methoxy Pectin [Type LM104AS, Hercules Inc.]

[0148] The extruder was set up as described in Example 1 and operated atjacket temperature of 250° F. and a feed rate of 15 lb/hr. However, twoliquid feed lines were placed at the feed orifice. The first deliveredwater, and the second delivered an aqueous solution of 27% (w/w) calciumlactate. The water feed rate was 1 ml/min., and the calcium solutionfeed rate was set at 4 ml/min. Orange oil [Citrus and Allied] with addedpolyglycerol ester emulsifier [Caprol 3G0, Witco Chemical Co.] at theratio 90:10 (w/w) was prepared and the liquid injected at 28 ml/min.into the fluid melt. The exit temperature of the matrix was 229° F. Uponcooling to ambient conditions, the collected product resulted in a hard,fracturable solid. This solid was characterized by DSC as a glass with aT_(g) of 39° C. The matrix was analyzed at 7.8 wt. % moisture [by KarlFisher] and 9.2 wt. % orange oil.

Example 7

[0149] A carbohydrate base consisting of 50 wt. % of 10 D.E.maltodextrin [Lodex 10, American Maize Co.] and 50 wt. % of 42 D.E. cornsyrup solids [Frodex 42, American Maize Co.] was fed at a rate of 15lbs/hr into an extruder as described in Example 1. Water plasticizer wasadded to the feed port at a rate of 2.5 mls/min. The encapsulate, acompounded onion flavor, was injected into the molten mixture through ajacket port using a metering pump at the rate of 12 mls/min. The exudatewas collected at ambient pressure. Upon cooling the solid matrixcontaining onion flavor was characterized by DSC as a glass with a T_(g)of 37° C. at 6.6 wt. % moisture (by Karl Fisher analysis).

Example 8

[0150] A carbohydrate matrix base is prepared as follows: 10 D.E.Maltodextrin (Soludex 10, Penwest Foods, Co.) is hydrated by theaddition with agitation of 5% (wt/wt) distilled water and the systemequilibrated to yield a pre-plasticized carbohydrate as a free-flowingmaterial. A buffering component composed of 12.4 parts citric acid(Pfizer) and 12.1 parts trisodium citrate dihydrate (Cargill) was mixedand blended. The mixture was milled in a Brinkmann laboratory impactmill with a single pass through a 0.5 mm screen to yield a fine,non-crystalline powder characterized as amorphous by DSC analyses (seeFIG. 1).

[0151] The extrusion base is prepared by immediately combining 80 wt. %of the maltodextrin with 20 wt. % of the milled buffer component. Themixture is then blended with the encapsulate citral (Aldrich ChemicalCo.) at a level of 5.0 wt. % of the total mixture. The flavor-basemixture is melt extruded in a Braebender single screw extruder, fittedwith a 1:1 compression screw. Heating zones 1, 2, and 3 were set atambient, 109° C., and 105° C. respectively and run at a screw speed of20 rpm. The solid exudate was characterized by DSC as a glass with aT_(g) of 41° C. and 7.2 wt. % moisture (by Karl Fisher Analyses) and acitral content of 2.6 wt. % by volatile oil analysis.

Example 9

[0152] A base consisting of CAPSUL®, a modified starch, (NationalStarch, Bridgewater, N.J.) was fed at a rate of 15 lb/hr into anextruder as described in Example 1. Water was added as a plasticizer ata rate of 10 ml/min. The encapsulate, orange oil, and emulsifier at a4:1 ratio were injected into the molten mixture through a jacket port ata rate of 16 grams/min. Upon cooling, the exudate formed a hard, densesolid. The product was analyzed to have a volatile oil content of 5.7%by weight. DSC analysis of the product shows a glass transition (T_(g))of 49° C.

Example 10

[0153] A mixture of 90 wt. % CAPSULE modified starch (National Starch,Bridgewater, N.J.) and 10 wt. % Amerfond fondant sugar (Amstar, NY,N.Y.) was fed at a rate of 15 lb/hr into an extruder as described inExample 1. Water was added as a plasticizer at a rate of 10 ml/min. Theencapsulate, orange oil, and emulsifier at a 9:1 ratio were injectedinto the molten mixture through a jacket port at a rate of 15 grams/min.Upon cooling, the exudate formed a hard, dense solid. The product wasanalyzed to have a volatile oil content of 8.3% by weight and a moisturecontent of 5.2%. DSC analysis of the product showed a glass transition(T_(g)) of 44° C.

Example 11

[0154] A modified starch base of CAPSUL® (National Starch,. Bridgewater,N.J.) was fed at a rate of 15 lb/hr into an extruder as described inExample 1. A 1:1 mixture of water:propylene glycol was added as aplasticizer at a rate of 16 ml/min. The encapsulate, orange oil, andemulsifier at a 9:1 ratio were injected into the molten mixture througha jacket port at a rate of 14 grams/min. Upon cooling, the exudate, bothwith and without encapsulate, formed a hard, dense solid.

[0155] Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. An encapsulation composition, comprising: (A)an encapsulate encapsulated in: (B) a glassy matrix of: (a) 95 to 100wt. % of a maltodextrin having 5 to 15 D.E.; or (b) 45 to 65 wt. % of amaltodextrin having 5 to 15 D.E. and 35 to 55 wt. % of a corn syrupsolids having 24 to 42 D.E.; or (c) 80 to 95 wt. % of a maltodextrinhaving 5 to 15 D.E., 1 to 15 wt. % of a salt of an organic acid, and 0to 15 wt. % of an organic acid; or (d) 25 to 80 wt. % of a maltodextrinhaving 5 to 15 D.E., 2 to 45 wt. % of a food polymer, and 10 to 30 wt. %of a mono- or disaccharide or corn syrup solids having 24 to 42 D.E.; or(e) 45 to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2 to 22 wt. %of a carbohydrate polymer having carboxylate or sulfate groups, 5 to 30wt. % of corn syrup solids having 24 to 42 D.E., and 0.2 to 2.0 wt. % ofa soluble calcium salt; or (f) 30 to 100 wt. % of a modified starch and0 to 70 wt. % of a mono- or disaccharide; or (g) 85 to 100 wt. % of amodified starch and 0 to 15 wt. % of a polyhydric alcohol.
 2. Thecomposition of claim 1, having a glass transition temperature of ≧35° C.3. The composition of claim 2, having a glass transition temperature of≧40° C.
 4. The composition of claim 1, wherein said matrix comprises (a)95 to 100 wt. % of a maltodextrin having 5 to 15 D.E.
 5. The compositionof claim 1, wherein said matrix comprises (b) 45 to 65 wt. % of amaltodextrin having 5 to 15 D.E. and 35 to 55 wt. % of a corn syrupsolid having 24 to 42 D.E.
 6. The composition of claim 1, wherein saidmatrix comprises (c) 80 to 95 wt. % of a maltodextrin having 5 to 15D.E., 1 to 15 wt. % of a salt of an organic acid, and 0 to 15 wt. % ofan organic acid.
 7. The composition of claim 1, wherein said matrixcomprises (d) 25 to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2 to45 wt. % of a food polymer, and 10 to 30 wt. % of a mono- ordisaccharide or corn syrup solids having 24 to 42 D.E.
 8. Thecomposition of claim 1, wherein said matrix comprises (e) 45 to 80 wt. %of a maltodextrin having 5 to 15 D.E., 2 to 22 wt. % of a carbohydratepolymer having carboxylate or sulfate groups, 5 to 30 wt. % of cornsyrup solids having 24 to 42 D.E., and 0.2 to 2.0 wt. % of a solublecalcium salt.
 9. The composition of claim 1, wherein said matrixcomprises (f) 30 to 100 wt. % of a modified starch and 0 to 70 wt. % ofa mono- or disaccharide.
 10. The composition of claim 1, wherein saidmatrix comprises (g) 85 to 100 wt. % of a modified starch and 0 to 15wt. % of a polyhydric alcohol.
 11. The composition of claim 1, whereinsaid encapsulate is selected from the group consisting of medications,pesticides, vitamins, preservatives, and flavoring agents.
 12. Thecomposition of claim 11, wherein said encapsulate is a flavoring agent.13. The composition of claim 12, wherein said flavoring agent isselected from the group consisting of natural extracts, oleoresins,essential oils, protein hydrolysates, aqueous reaction flavors, andcompounded flavors.
 14. An encapsulation composition, comprising (A) anencapsulate encapsulated in: (B) a glassy matrix of: (a) 95 to 100 wt. %of a maltodextrin having 5 to 15 D.E.; or (b) 45 to 65 wt. % of amaltodextrin having 5 to 15 D.E. and 35 to 55 wt. % of a corn syrupsolids having 24 to 42 D.E.; or (c) 80 to 95 wt. % of a maltodextrinhaving 5 to 15 D.E., 1 to 15 wt. % of a salt of an organic acid, and 0to 15 wt. % of an organic acid; or (d) 25 to 80 wt. % of a maltodextrinhaving 5 to 15 D.E., 2 to 45 wt. % of a food polymer, and 10 to 30 wt. %of a mono- or disaccharide or corn syrup solids having 24 to 42 D.E.; or(e) 45 to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2 to 22 wt. %of a carbohydrate polymer having carboxylate or sulfate groups, 5 to 30wt. % of corn syrup solids having 24 to 42 D.E., and 0.2 to 2.0 wt. % ofa soluble calcium salt; or (f) 30 to 100 wt. % of a modified starch and0 to 70 wt. % of a mono- or disaccharide; or (g) 85 to 100 wt. % of amodified starch and 0 to 15 wt. % of a polyhydric alcohol, wherein saidcomposition is prepared by a process comprising: (i) mixing (a), (b),(c), (d), (e), (f), or (g) with a liquid plasticizer and an encapsulatein an extruder to obtain a melted matrix; and (ii) extruding said meltedmatrix.
 15. The composition of claim 14, having a glass transitiontemperature of ≧35° C.
 16. The composition of claim 14, having a glasstransition temperature of ≧40° C.
 17. The composition of claim 14,wherein in said mixing step, (a) 95 to 100 wt. % of a maltodextrinhaving 5 to 15 D.E. is mixed with said liquid plasticizer and saidencapsulate.
 18. The composition of claim 14, wherein in said mixingstep, (b) 45 to 65 wt. % of a maltodextrin having 5 to 15 D.E. and 35 to55 wt. % of corn syrup solids having 24 to 42 D.E. is mixed with saidliquid plasticizer and said encapsulate.
 19. The composition of claim14, wherein in said mixing step, (c) 80 to 95 wt. % of a maltodextrinhaving 5 to 15 D.E., 1 to 15 wt. % of a salt of an organic acid, and 0to 15 wt. % of an organic acid is mixed with said liquid plasticizer andsaid encapsulate.
 20. The composition of claim 14, wherein in saidmixing step, (d) 25 to 80 wt. % of a maltodextrin having 5 to 15 D.E., 2to 45 wt. % of a food polymer, and 10 to 30 wt. % of a mono- ordisaccharide or corn syrup solids having 24 to 42 D.E. is mixed withsaid liquid plasticizer and said encapsulate.
 21. The composition ofclaim 14, wherein in said mixing step, (e) 45 to 80 wt. % of amaltodextrin having 5 to 15 D.E., 2 to 22 wt. % of a carbohydratepolymer having carboxylate or sulfate groups, 5 to 30 wt. % of cornsyrup solids having 24 to 42 D.E., and 0.2 to 2.0 wt. % of a solublecalcium salt is mixed with said liquid plasticizer and said encapsulate.22. The composition of claim 14, wherein in said mixing step, (f) 30 to100 wt. % of a modified starch and 0 to 70 wt. % of mono- ordisaccharide is mixed with said liquid plasticizer and said encapsulate.23. The composition of claim 14, wherein in said mixing step, (g) 85 to100 wt. % of a modified starch and 0 to 15 wt. % of a polyhydric alcoholis mixed with said liquid plasticizer and said encapsulate.
 24. Thecomposition of claim 14, wherein said encapsulate is selected from thegroup consisting of medications, pesticides, vitamins, preservatives,and flavoring agents.
 25. The composition of claim 24, wherein saidencapsulate is a flavoring agent.
 26. The composition of claim 25,wherein said flavoring agent is selected from the group consisting ofnatural extracts, oleoresins, essential oils, protein hydrolysates,aqueous reaction flavors, and compounded flavors.
 27. The composition ofclaim 14, wherein said liquid plasticizer is selected from the groupconsisting of water, an aqueous solution of a maltodextrin, an aqueoussolution of a mono- or disaccharide, an aqueous solution of a corn syrupsolid, an aqueous solution of an acid and a salt of the acid, an aqueoussolution of a calcium salt, and an aqueous solution of a polyhydricalcohol.